Servicing of a food or pharmaceutical production line currently has strict guidelines that require exclusion zones from which various material packaging components and accessories are excluded. In spite of these exclusion policies, plastic debris does enter production lines and with even a single piece of plastic entering a production stream, large quantities of otherwise usable product must be discarded. Rules regarding processing of ground meat are exemplary of those that require discard of the product if possibly contaminated. Common plastic packaging or service articles that are inadvertently brought into production exclusion zones include aerosol cans, grease cartridge tubes, grease tube caps, plastic fiber toweling, packing straps, pail lids, jar caps, and personal protective clothing.
Metal detectors are commonly found on food processing lines to assure that metal shards that represent a laceration hazard do not end up in food products. Similarly, pharmaceutical and biomedical device production are also vulnerable to not only the hazards associated with metal debris ending up in product streams, but also the prospect that such metal can degrade active pharmaceutical ingredients or serve as a potential source of infection. Numerous technologies are known to the art to detect spurious metal within a production line. These technologies include a transmitter coil-receiver coils for metal detection systems, systems that use radio frequencies, and magnetic field based systems. In recognition of the fact that some metallic materials are not ferromagnetic and simultaneously not particularly good electrical conductors, x-ray scanners and other electromagnetic field (emf) spectral region spectral detection techniques have been added to food and pharmaceutical product lines to facilitate the detection of a wider range of contaminants.
Many industries have a need for metal detectable polymers and articles made therefrom. By way of example, a food, medical, or pharmaceutical production line maintains tight audit control of service items that enter the manufacturing facility to assure such items do not accidently enter the production stream as a contaminant that can be fragmented into dangerous shards. Historically, plastics have been precluded from some environments due to the inability to locate such articles with product screening X-ray or magnetic detectors. Recently, plastic articles have been developed that are filled with metal particulate or barium sulfate, as detailed in U.S. Pat. No. 8,980,982 that are detectable with magnetic or X-ray detectors, yet still process as injection moldable thermoplastics and operate in a manner similar to their unfilled conventional counterparts.
By way of example, U.S. Pat. No. 5,897,673 teaches fibers containing fine metallic particles that are cross-linked to the polymeric fiber. While various pure metals are contemplated in the literature, little attention has been paid to the unique problems associated with stainless steel particulate. As many foods and manufactured substances can only be exposed to stainless steel, the lack of stainless steel particle filled fibers precludes the usage of many useful articles from these controlled manufacturing sites. By way of example various wipes, scrub pads, hair covers, suits, aprons and shoe covers and other manufacturing aids or personal protective equipment if made from stainless steel containing fibers could allow better quality control of manufacturing with less stringent audit processes as any such articles lost in a production stream could be detected by X-ray or magnetic anomaly.
Thus, there exists a need for a thermoplastic fiber filled scrim structure with detectable particulate or functional additives. There also exists a need for such fibers that process and retain properties of conventional thermoplastic fibers to promote production of various articles from fibers that have the added benefit of being X-ray or magnetically detectable while operating in a manner similar to conventional articles.